Medtronic releases MARVEL 2 data on leadless pacing in AV block

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Medtronic has announced results from the MARVEL 2 (Micra Atrial Tracking Using A Ventricular accELerometer) study. A press release from the company says that the study shows that an investigational set of algorithms in the Micra Transcatheter Pacing System (TPS) significantly improves synchrony and cardiac function in patients with atrioventricular (AV) block. The results from MARVEL 2 are to be presented during a Featured Science session at American Heart Association 2019, the AHA Scientific Sessions, and were published today in JACC: Clinical Electrophysiology.

Based on positive results from both the MARVEL and MARVEL 2 studies, Medtronic says it has submitted a new leadless pacemaker, Micra AV, to expand the indicated population to AV block and normal sinus rhythm. This submission is currently under US food and Drug Administration (FDA) review. In its statement, the company points out that the Micra AV submission is not approved and the product is not currently available for sale in the US. By federal law, Micra AV is investigational use only.

MARVEL 2 evaluated 75 patients with a Micra TPS at 12 centres in Hong Kong, Malaysia, Europe and the USA. Investigators evaluated the safety and effectiveness of accelerometer-based atrial sensing algorithms, which were downloaded to the Micra TPS device. Forty patients had complete heart block and normal sinus rhythm and were eligible for inclusion in the primary efficacy analysis, while all 75 patients were included in the primary safety objective. Investigators evaluated the ability of the Micra accelerometer to monitor and detect atrial contractions and enable coordinated pacing between the atrium and ventricle, thereby providing AV synchrony.

Using continuous device telemetry and an electrocardiogram Holter monitor, patients’ AV synchrony was measured during 20 minutes of rest and during single-chamber ventricular (VVI) pacing. The study’s primary efficacy objective was met, with a significantly greater percentage of complete heart block patients with normal sinus rhythm having >70% AV synchrony during algorithm-mediated AV synchronous pacing (38 of 40 patients, 95%) than VVI pacing (0 patients, p<0.001 for proportion of patients with >70% synchrony). The median percent AV synchrony was 94.3% during AV synchronous pacing compared to 26.9% during VVI pacing.

In addition, blood flow from the left ventricle (velocity time integral, a proxy for stroke volume), increased by 1.7 cm (on an absolute scale, 95% CI 0.7–2.7cm, p=0.002; or 8.8% on a relative scale) during AV synchronous pacing compared with single-chamber ventricular pacing mode in patients with normal sinus rhythm with complete heart block.

The study’s primary safety objective was met, with no pauses or episodes of pacing-induced tachycardia reported during algorithm mediated AV synchronous pacing in any of the 75 patients.

“The results of MARVEL 2 build on the original promising MARVEL results and provide the strongest evidence to date that accelerometer-based atrial sensing with the Micra leadless pacemaker has the potential to provide improved AV synchrony in AV block patients, who make up approximately 40% of the pacemaker population worldwide,” said Rob Kowal, chief medical officer, vice president of medical affairs in the Cardiac Rhythm and Heart Failure division, which is part of the Cardiac and Vascular Group at Medtronic. “This first-of-its-kind approach to pacing is another example of Medtronic’s commitment to meaningful product innovation that will help patients around the world.”

The Micra TPS was approved by the FDA in April 2016 for patients who need a single-chamber pacemaker, and Medtronic says it is the first and only leadless pacemaker approved for use in the USA. It says that, unlike traditional pacemakers, the Micra TPS does not require leads or a surgical “pocket” under the skin, so potential sources of complications related to such leads and pocket are eliminated – as are any visible signs of the device.


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